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2005 STS N*, 1SF, 144K mi.
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Discussion Starter #1
I've checked at the battery for a parasitic drain. Nothing...and that's with multiple meters, one a Fluke.

Disconnected the one connector on the OnStar control module in the trunk, the one which is black and second from the bottom. Have yet to be able to tell a difference.

I drive Pearl, daily, save for Friday, Saturday, and Sunday, when she typically stays parked, as we tend to use one of the other cars (it's easier for my partially-crippled wife and I to get in/out of the RX300 and the Jeep ZJ). Every day, she starts semi-normally. The starter doesn't spin as quickly as I expect, but all cars are different.

Some afternoons, there is a dip into the rrrrr-rrrrr sound, but she always fires. The garage is never all that cold, and there doesn't appear to be any difference in behavior due to season.

This is the second battery in two years, and I went to the largest one which fits. After replacing it last time, we went out-of-town in a different car for several days. Came back, the battery was 10 days old, an Interstate, IIRC, and sure enough, just enough juice to unlock the doors.

I put a charger on her every Thursday afternoon, and remove it every Sunday evening, but this should be wholly unnecessary. The Ultra Gauge shows ECU voltage while running is 13.5-14.0 after starting, and is down to 13.2-13.4 after my 30 mile, almost 100% freeway, drive home. The alternator puts out proper voltage. The terminals are clean, the battery is full, using only distilled water to replenish when needed, but what is going on?

I know about wet-cell batteries, having six of them in our motorcoach, and being able to get 10-12 years out of them before replacing. Typically a plate breaks free, and there's not much you can do about that. The STS's battery isn't sulfated, run low on electrolyte, abused...nothing.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The Ultra Gauge shows ECU voltage while running is 13.5-14.0 after starting, and is down to 13.2-13.4 after my 30 mile, almost 100% freeway, drive home. The alternator puts out proper voltage. The terminals are clean, the battery is full, using only distilled water to replenish when needed, but what is going on?
Your engine running and charging voltages are too low. You must have cable, terminal, alternator or voltage regulator problems.

Normal running voltages, fully charged, should be about 14.1 - 14.6 volts - always. MAYBE a dip to 13.8 at night idle, lights on. The droop to 13.2 is unsatisfactory. Even a Battery Minder puts out 13.1 - 13.3 volts at full charge maintenance float - and with near-zero amperage. That's nowhere near enough "power" to run the car, much less charge the battery - an alternator/regulator always (is supposed to) puts out a slightly high voltage with varying amperage (depending on electrical loads) to maintain a fully charged battery with the engine running. A fully charged battery, disconnected from anything for at least a half hour, should show 12.6 volts on a VOM. Battery connected to the car, the DIC voltage will always be less due to electrical loads even with the key in the ON position only.
 

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2005 STS N*, 1SF, 144K mi.
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Discussion Starter #3 (Edited)
Looks like I dig into first, cable connections/resistance measuring, and if nothing shows itself...sigh...alternator/regulator.

The regulator on these must be built in to the alternator...I haven't seen a stand-alone regulator in decades (and they really are a good idea, _especially_ the manually adjustable ones!).

I thought it might be a connector at the starter, but I've yet to dig around under there for it, specifically, so I'm not 100% certain how accessible it is. I did clean under the ground strap at the fender, as it's painted (!), then put dielectric grease on the area so it wouldn't immediately rust.
 

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2018 Camaro 2SS/NPP/F55/AQJ, Sold: 2015 Camaro, 2006 STS (EXP) 1997 Seville STS (EXP)
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...a little offtopic, but...

Normal running voltages, fully charged, should be about 14.1 - 14.6 volts - always. MAYBE a dip to 13.8 at night idle, lights on. The droop to 13.2 is unsatisfactory.
@sub:
...not on a sigma-based STS...they should...and are running in a range from 12.9 to 13.4 V...
...with a good battery it should cycle down to a ~12.9 volt reading on the DIC after a while...(mostly it's something between 12.8 - 13.2 volts) ...if the lights are on it's a drop down to ~13.4 volts...
...has something to do with the cars "Electrical Power Management (EPM)"-system...
..."EPM"-description here in post #6:
http://www.cadillacforums.com/forums/cadillac-sts-v-series-forum/134790-new-gm-battery-reading-13-0-a.html

...again...different animal...;)

...sigma-STS's system is totally different to the E/K-Body and K(G)-platform...

offtopic end
 

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2006 STS V8 AWD, '95 Ford Ranger
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A very quick but effective check of the battery/charging system is if the headlights appear to flare at night when going from idle to driving. When you come home from a drive and have the high beams shining on the garage door take the engine from idle to about 1500RPM several times and see if the lights change brightness. If they turn orange at idle you have a problem somewhere. If nothing changes with RPM you're probably in good shape.
 

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2005 STS N*, 1SF, 144K mi.
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Discussion Starter #6
I don't think this is valid with HID headlamps, however.

You might be able to see it in the other incandescent lamps, but I think it'd have to be pretty bad to notice with something like a marker lamp.
 

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2007 STS-V
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193 Posts
High beams are incandescent. This is an excellent suggestion. It is impossible to tell what is going on with this platform with a voltmeter alone. The system is under computer control. You would have to see the PWM signal to the alternator with a scope to tell if it was instructed to charge but not able to do it.
 

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2006 STS 1SF N* RWD NAV F55
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mckelleyb: what kind of charger are you using ? there are ALL types,
Automatic ? Float ? computer controlled devices ?
also, why are you mentioning using distilled water at all, after 1 or 2 years,
the battery should NOT NEED any water.
Does you car still have a protective cover on the battery ?
Happy Motoring. :cool2::stirpot::cool2:
 

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2006 STS4 V8 1SG & 2007 STS V8 1SE
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Even 'maintenance-free' batteries require distilled water from time to time. (Another example of modern marketing for my collection of ironies!) Only sealed batteries are truly 'maintenance-free'.

Why does the STS chew up batteries? The original ones were of barely adequate rating for the task and if the car is not used as a daily driver, the slightest fault can quickly grow into battery failure. The automotive battery industry association BCI, lists the STS Type 101 battery at 540 CCA, whereas the Type 78 fits OK and is widely offered in ratings of 800 CCA & up, almost 50% higher. Proof positive comes right from GM in all the warranty replacements & the ultimate upgrade in the 2008 model year. Look at all the other genuine faults they didn't cover!

There is really nothing wrong with most of the Delco batteries, except getting used hard and not given sufficient recharging, or being recharged too quickly. Fast charges are almost as hard on batteries as high current draws. It comes down to current flow... Amps cause heat. Batteries in a low state charge faster at first (sounds good) but causes more heat (the batteries' enemy.) We have 150 Amp alternators. Imaging a battery starting a cold car, drawing out 500 amps for 5 seconds and then taking in over 100 amps for 30 seconds. Meanwhile, it unevenly warmed-up from around freezing to room temperature. Think some electrolyte boiled here & there?

We were lucky. Our Delco's lasted 6+ years and could have gone farther. Now we are using Optima's, and they work great, too. But we care for our cars, too. They're in a garage.
 

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2005 STS N*, 1SF, 144K mi.
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Discussion Starter #13
mckelleyb: what kind of charger are you using ? there are ALL types,
Automatic ? Float ? computer controlled devices ?
also, why are you mentioning using distilled water at all, after 1 or 2 years,
the battery should NOT NEED any water.
Does you car still have a protective cover on the battery ?
Happy Motoring. :cool2::stirpot::cool2:
I've used three different ones. A trickle Battery Tender, something like 2A, max. Another 2/10/20A one which I'm not convinced was particularly useful, can't remember who it's made by, but it was new, and computer-controlled. Finally, a wheeled 2/20/40/200 amp Schumacher, which I know puts out a disturbing amount of juice, and behaves properly...it'll crank back the power it's sending, depending on voltage read.

"Maintenance free" batteries are anything but. In fact, if you remove the sticker on the top, you'll find fill caps, unless it's a gel cell or similarly, truly sealed battery.

I removed the protective cover when I moved to the larger size. Wholly unnecessary, based on my 30+ years of motor vehicle ownership.
 

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2008 STS Platinum
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21 Posts
I have experienced similar battery drain issues with my 2008 STS 3.6 Platinum. BTW, with just a Fluke 87, it is possible to measure low amperage draw with confidence. And if you are careful, you can do it without ever completely removing 12VDC from the vehicle just plant one probe on the battery terminal and the other on the cable before you remove the cable connection from the battery. I measured 55mA after about 2 minutes of the engine being shut off. I came back about 15 minutes or so later and measured about 20 to 30mA (as I recall). The amperage draw seems to back down in steps just like the car is slowly going to sleep. I don't know what to expect for this vehicle so if someone has a spec for this, I would really appreciate seeing it. The longest I have observed a (Sears Diehard Advanced Gold 48 month - 760CCA @ 0 Deg Fahrenheit) battery last is about 22 months! The heat in Florida all year round does speed up the chemical reaction in any battery left outside - but come on...only 22 months of life??!!

My voltage was sagging too during idle. I would often see 12.9V during the blistering heat during stop and go traffic. (Never seen any weird headlight behavior.) A local auto electric shop replaced the regulator in the alternator and it seemed that the voltage stayed more in the range of about 13.5 to 14. But then the cheap replacement regulator (Transpo brand) failed and I had to replace the whole alternator since you cannot get an OEM replacement regulator from Denso!:mad2::rant2:
 

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2006 STS4 V8 1SG & 2007 STS V8 1SE
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There was a thread about 4 years ago detailing the 'unwind' sequence of the STS. As I recall, it takes hours to drop to levels that many cars reach much faster.

The STS begins to 'wake up' before the driver even touches the door, too. Just walking up to the car with a matched fob starts activating systems.

As in sub-atomic physics, the act of observing a phenomenon, has an effect on that phenomenon.

IMHO, your original voltage regulator was superior to its aftermarket replacement. It was likely working as designed. I would only let a master Cadillac tech rebuild an STS alternator. When I need one, I'll be sorely tempted to buy new.
 

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...The starter doesn't spin as quickly as I expect, but all cars are different.

Some afternoons, there is a dip into the rrrrr-rrrrr sound, but she always fires. The garage is never all that cold, and there doesn't appear to be any difference in behavior due to season.
Everyone's added relevant comments to the battery part, but I want you to know that my starter was doing the same thing. Sometimes the spin rpm seemed slow for the first few revs then it would pick up speed, not as much as it seemed to need, but it always eventually started. It also seemed to take longer to light up, even with new coils and plugs.

Then one morning on my way to work I stopped in at *bucks for a mocha, and came back out and, nothing. Everything else worked but it wouldn't crank. I started kicking myself in the butt for not heeding the starter failure warning signs.

I had it towed home, bought a NAPA starter and replaced it. The old starter rattled like there was a lot of broken pieces inside. Then I hit the button and it fired right up. It spun instantly at a very high rpm and started faster than it had in a long time. Needless to say I was thrilled! But the NAPA starter was semi-DOA and had to pull it out and replace it with another one.

Now it starts perfectly, first time and almost instantly.

HEED THE WARNING SIGNS! REPLACE YOUR STARTER BEFORE IT LEAVES YOU STRANDED.

They're only about $160 + $35 for the manifold plenum gasket set. The dealer wanted $852 to do the job.
 
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